Zip Attachment on S/MIME signed messages

[somjue]

If Zip Attachment = yes on a S/MIME signed message (Content-Type: multipart/signed;), the MessageAttachments.zip is attached to the wrong mime-part, so some mail clients (Thunderbird) won't show the attachment. Attached two sample e-mails one with current result and one with correct headers.

Maybe it's also to discuss, to disable Zip Attachment because signature will be invalid after attachment zip.

Regards,
Juerg

current-wrong.txt
correct.txt

[github-actions]

Thank you for submitting your first issue to MailScanner! We will respond to you soon!

I agree that Zip Attachment doesn't make much sense with an S/MIME message. I'll try to wrap my head around why the mine boundary is missing and work on this.